Zero-Dimensional Organic-Inorganic Hybrid Copper-Based Halides with Highly Efficient Orange-Red Emission

Area of Science:

• Materials Science
• Solid-State Chemistry
• Optoelectronics

Background:

• Lead-free metal halides are attractive for optoelectronic applications due to their low toxicity and tunable emission properties.
• Developing efficient red light-emitting materials with high photoluminescence quantum yield (PLQY) is crucial for LED lighting and displays.
• Existing materials often face challenges in meeting stringent color coordinate and efficiency requirements.

Purpose of the Study:

• To synthesize and characterize novel lead-free copper-based halide materials for efficient light emission.
• To investigate the relationship between material structure and luminescent properties, particularly for orange-red emission.
• To evaluate the potential of these materials in practical optoelectronic devices like LEDs.

Main Methods:

• Synthesis of novel zero-dimensional copper-based halide compounds.
• Photoluminescence spectroscopy to measure emission spectra and PLQY.
• Fabrication and testing of a prototypical light-emitting diode (LED) device.

Main Results:

• Successfully synthesized three lead-free copper-based halide materials: ((R)-(+)-α-PEA)₄Cu₄I₄, ((S)-(-)-α-PEA)₄Cu₄I₄, and (β-PEA)₄Cu₄I₄.
• Achieved efficient orange-red broad emission with a highest PLQY of 73.6% for PEA₄Cu₄I₄.
• Demonstrated large exciton binding energies and Huang-Rhys factors, leading to efficient self-trapped exciton emissions.
• Fabricated a working orange-red LED device showcasing the material's applicability.

Conclusions:

• The synthesized lead-free copper-based halides exhibit excellent orange-red luminescence and high PLQY.
• Zero-dimensional structures with high exciton binding energies are key to efficient self-trapped exciton emission.
• These materials hold significant promise for next-generation lighting and display technologies.